Regarding out of state property, est. trust, modified in 07. Is this acquired marital?

based upon this fact pattern the property is an inheritance and your name is not and was not on it so it is not marital property.

How easy would it be to get custody of my younger brother, and how expensive would that be

You can file a petition for relative custody under chapter 751, Florida Statutes.

My ex has decided since my husband wants to adopt my daughter to sign over his parental rights to our daughter, where do i start

You can file a petition for step-parent adoption. If everyone consents it is easy, but you still need a lawyer.

Im not getting child support payment as ordered by the court. My ex is currently behind $2800 in payment.

file a motion for contempt plus a motion for an income withholding order.

Martial Separation Agreement - Contempt Issue/Concern

This is not support however you could file a motion with the court to recoup your costs. Or in the alternative you could pay it off now then hit...

What can I do myself?

if the attorney is not finalizing the paperwork then have your lawyer do it.

When contemplating divorce, could it risk my alimony and be used against me later, to meet amicably and text an old boyfriend?

Probably does not matter but don't risk it.

Can I stop a mom from taking her child that has been living with me over a year out of state.She moved out of state and left kid

If you are the father of the kids yes otherwise you have no case, other than to call DCF.

I am currently going through a divorce and a custody battle and my wife is making false allegations against me. What can I do?

Get her under oath at a hearing then set her up for perjury. Fight, you have no other choice.

you can file whatever motions you want and have them heard by the court, yes.